1. Field of the Invention
The present invention relates to an IC testing apparatus for testing a variety of electric parts, such as semiconductor integrated circuit devices (hereinafter referred to as an "IC" or "ICs"), particularly relates to an IC testing apparatus having a device for giving a low temperature thermal stress.
2. Description of the Related Art
An IC testing apparatus called a "handler" conveys a large number of ICs held on a tray to the inside of a testing apparatus where the ICs are made to electrically contact a test head, then the IC testing unit (hereinafter, also referred to as a tester) is made to perform the test. When the test is ended, the ICs are conveyed out from the test head and reloaded on trays in accordance with the results of the tests so as to classify them into categories of good ICs and defective ones.
When roughly dividing handlers of the related arts in terms of forms of giving a thermal stress, there are handlers of a chamber form in which the ICs to be tested are reloaded to an exclusive tray called a test tray, transferred into a thermal stress applying chamber and made to become a predetermined temperature before being pressed against a test head in a state being carried on the test tray, and handlers of a heat plate form in which the ICs to be tested are carried on a heat plate (also referred to as a hot plate) to be given a high temperature thermal stress and are pressed against the test head while a plurality of the ICs are simultaneously picked up by a pick-up head.
Especially, when testing by giving a low temperature thermal stress, a handler of the chamber form is mainly used, wherein a low temperature stress of for example about -30.degree. C. is given to the ICs by introducing liquid nitrogen into the chamber.
When giving a low temperature stress at a handler, a supply source of liquid nitrogen is necessary as explained above. In the related art, it was drawn to the handler from a liquid nitrogen storage provided separately from the handler by using a plant piping system, or it was supplied by providing a liquid nitrogen cylinder near the handler to supply it to the handler through pipes, etc.
When configuring to press to send the liquid nitrogen by plant pipes from the liquid nitrogen storage provided separately from the handler, however, there have been disadvantages that a space for handling the plant pipes became limited and costs on the equipment for heat-retention and others, became high. Although such disadvantages can be solved when providing the liquid nitrogen cylinder near the handler, a new disadvantage like troublesomeness of exchanging the cylinder arises.
Further, since liquid nitrogen is a substance which has to be handled with precautions and cannot be used carelessly. Thus, it is necessary to be aware of sufficient countermeasures which also ends up in an increase of the cost.
Accordingly, inventors of the present invention developed an IC testing apparatus having a equipment for giving a thermal stress in place for liquid nitrogen. However, the thermal stress applying equipment and the handler have to be connected by a duct, etc. in order to supply a cold air from the thermal stress applying equipment to the thermal stress applying chamber. In such a case, since the duct has to be removed for maintenance of the inside of the thermal stress applying chamber and exchange of a change kit, it has been demanded to develop along with it the connection structure of the duct capable of keeping a sufficient air tightness and being detached and attached easily.